Submitted to: Euphytica
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/1/2002
Publication Date: 10/31/2002
Citation: PEDERSEN, J.F., KOFOID, K.D. VARIABILITY AND RELATIONSHIPS AMONG 12-HOUR IVDMD, STARCH, OIL, PROTEIN, AND PHYSICAL CHARACTERISTICS OF 16 SORGHUM CONVERSION LINES. EUPHYTICA. 2002. Interpretive Summary: Recent research has shown that digestion of corn by cattle can be predicted by simply measured physical and chemical properties of the grain. It would be very desirable to utilize such simply measured traits to predict feed value of sorghum. This study documents the range of variation in digestibility, crude protein, oil, starch, and hardness of grain from 16 widely divergent sorghum lines, and determines the predictive ability of the various traits on digestibility. Unlike in corn, prediction of digestibility using simply measured traits was poor in this set of sorghum lines. The weak relationships among the various traits should not necessarily be viewed as negative. In this study, individual lines were identified that possess unique combinations of traits. For example, SC242 is highly digestible, has high crude protein, does not contain a pigmented testa, and is quite hard. It should have good feed value and would harvest and process without appreciable cracking and breaking of seeds. The line SC334 contains a highly pigmented testa, is very soft and very digestible, and may have value in new specialty applications capitalizing on the high antioxidant potential of highly pigmented testa-containing sorghum. These results indicate that such combinations could be made by breeders to satisfy special market needs.
Technical Abstract: A factor frequently identified as a key to understanding sorghum [Sorghum bicolor (L.) Moench] feed value to ruminant animals is rate of starch digestion. Recent research in corn (Zea mays L.) has established a strong predictive ability of rumen starch degradation from grain physical and chemical parameters. It was therefore important to determine whether similar relationships could be established in sorghum. The objectives of this study were to determine: 1) range of variation for 12-hour in vitro dry matter disappearance (IVDMD), chemical, and physical grain quality parameters among 16 sorghum conversion lines; and 2) to establish the strength of the relationships of these characters. Entries were grown at Ithaca, Nebraska in 1991 and 1992 in a randomized complete block with four replications. Line effects were significant for 12-hour IVMVD, crude protein, oil, starch , individual seed weight, and hardness. The only traits significantly correlated with 12-hour IVDMD were crude protein and hardness, with r<-0.32 for testa and non-testa-containing lines. Stepwise regression similarly revealed poor predictive ability for any of the traits on 12-hour IVDMD. Unlike corn, prediction of digestibility from simply measured physical parameters was not possible in this set of 16 sorghum lines. However, the lack of strong relationships provides opportunity to select lines with unique combinations of traits for individual targeted needs or markets.